Open-hearth process of refining steel.



G. BARBANSON & M. LEPERSONNE.

OPEN HEARTH PROCESS OF REPINING STEEL. APPLICATION FILED APR.26, 1910.

1,08%152 Patented June18,1912.

GASTON BARBANSON AED MAX LEPERSONNE, BRUSSELS, BELGIUM.

OPEN-HEARTH PROCESS OF REFINING STEEL.

Specification of Letters Iatent.

Patented June 18, 1912.

Application filed April 26, 1910. Serial No. 557,754.

To all'whom it concern:

Be it known that we, GASTON BARBAusoN and MAX LEPnRsoNNE,-citizens ofthe Kingdom of Belgium, residing at Brussels, Belgium, have inventedcertain new and useful Improvements in the -Open-Heart.h Process ofRefining Steel; and we do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and usethesame.

The invention has for its object tocarry out the said process, namelythe refimng of steel in the open hearth furnace, by means of coal dustheating.

Heating with coal dust fuel has already been practised for metallurgicalpurposes but heretofore the process has not been carried on in such amanner as to profit'by all the advantages ofthis mode of heating. Forexample, with the idea of more satlsfactorily attaining the hightemperature necessary, the air required for the injection and combustionof the coal dust has been introduced in a highly heated condition, sothat the coal dust was entirely or partially gasified a long time beforeignition of the flame the heating thus obtained was there-- fore gasheating, and the flames became so large that they could not beconcentrated, as it is desirable that they should be on selectedportions of the bath. When working with cold air, it was considerednecessary to pro vide combustion chambers, with the result that theheat, being generated in a compara tively large space, could not beconcentrated.

For these reasons the necessity for obtaining heat in a concentratedform, for steel making, has not up to the present been met in anyadvantageous manner, except by the application of the electric currentas the means of heating. It is, however, certain that the heat generatedby electric energy is, even under the most economical conditions ofproduction, more costly than the heat obtained by the combustion ofcoal.

The present invention aims at employing coal dust heating (by means ofwhich an extraordinary degree of heat can be obtained) in such a manneras to enable nearly the same result to be obtained as by electricheating. To arrive at this result, care is taken to obtain as short aflame as possible, this bein applied, in the most direct mannerposslble, to the bath to be heated.- To this end, the nozzles throughwhich the coal and the air or the mixture of coal and air is inected arelocated at as short a distance from the bath as is feasible; thisdistance, which 1s a function of the mean length of the flame obtalned,may advantageously be about forty inches. Moreover, in order to achievethe desired object, it is advantageous to blow in the air in merely aslightly heated condition, because in this way thepremature gasificationof the coal is prevented, thus precludlng an undesirable increase in thevolume of ame.

The point at which the maximum temperature is developed may be adjustedat will by regulating the velocity of the inected air. It follows fromthis that the maximum temperature of the flame can be projected, atwill, on to different portions of the bath. To obtain the highestpossible temperature, it is advisable to arrange the mixture of coaldust and air in such a manner that neither of the two elements is 1nexcess; nevertheless, an excess of air may, when the operation demandsit, be provided, thus furnishing an oxidizing flame; or an excess ofcarbon can be given. In the latter contingency a deoxidation of the bathcan be brought about, and, in some cases an addition of carbon to thebath may thus be supplied.

In the accompanying drawing I have shown an apparatus for carrying outmy process by way of example.

a is a hopper containing the coal dust, which is conveyed by a worm 6,into a pipe 0, which is joined to the air pipe at. In this latter, theair supplied by a fan 6 mixes with the coal .dust, the mixture en teringthe furnace by way of the nozzle f.

Ignition occurs .at a certain distance from the nozzle, and the flameimpinges directly on the bath of metal 7L lying in the hearth g of thefurnace. The products of combustion escape through the flue 7'.

It will be noted that the outlet for the products of combustion z is ata point opposite to the end' of the hearth where the combustion nozzle fprojects into the furnace. By this arrangement, the advantages obtainedare, that the flame from the nozzle can impinge directly against thesurface of the bath 7:. and without being diverted or interfered with.The nozzle f is so arranged that the flame therefrom will directlyimpinge against the bath, whereby, the heat of combustion is caused toact directly upon said bath at the proper point, and said bath is not,as heretofore, merely acted upon by the gases of combustion, due to saidflame. For this purpose, the nozzle f is arranged at a distance abovethe level of the bath h which is not greater than the distance from thepoint of ignition, and which is preferably somewhat less than saidlength. Thereby, and by virtue of the fact that the air mixed with thepowdered fuel is at a low temperature, the premature gasification of thefuel is prevented and the ignition takes place directly on the bath ormaterial treated, the generated heat of which in turn serves to maintainthe flame which generally spreads over the bath or material inthin'sheet-like form. By arranging the inlet from the fuel duct .feedpipe (2 into the air pipe 03 at a point a" substantially to the rear ofthe tapering nozzle f, the fuel and air are uniformly commingled therebyforming a homogeneous mixture thus considerably aiding the ignitionat-the reaction point of the bath. By such arrangement, we are enabledto utilize powdered fuel, such as coal dust, in such a way as to obtainsubstantially the same advantages that flow from the use of theelectricarc, at a cost much lower than when such electric arc isemployed.

By the above process great uniformity and a homogeneous composition orproportion of the feed are attained; and those familiar with the artwill readily understand from their own experience the various points inthe process at which to vary the character of the fuel and air feed,particularly in regard to its oxidizing, neutral, or reducing character.Moreover the shortness of the distance. between the mixing of the fuelwith the blast and the point of entry into the furnace is of greatadvantage, as, the shorter this distance is, the less chance will therebe of the fuel becoming even partially gasified or of the fuel settlinginto a particular localized portion of the cross section of the blast.

Having thus described our invention, what we claim as new, and desire tosecure by Letters Patent is: v A

1. In the manufacture of steel, the process which consists in subjectingthe materials by the open hearth furnace the method of heating the bathconsisting informing a short flame by' directing an air'blast onto thesurface of' the bath through'a tube the nozzle of which is-atapoint-adjacent to the surface of said bathand showering coal dustdirectly and continuously into said air blast at a point immediatelyexterior to the furnace. a 1

3. Inthe process. of manufacturing steel by the open hearth furnace, themethod of heating the bath consisting-in mixing air and fuel dust at. apoint immediately external to the furnace, causing the '-combustion ofsuch mixture at a point immediately over the bath and directing theflame of combustion into direct impingement against said bath.

4, In a method ,of obtaining steel in open A hearth-furnaces a processoftreating the bath consisting in highly heating thejsame,

mixing homogeneously a powdered combustible with air at .a' temperaturebelow that at which the combustible would become gasified, and thendirectingithe said homogeneous mixture against the bath, the combustionof the mixture being effected instantly and completely by' the hightemperature in the interior of the furnace.

5. In an open hearth process for the manufacture of steel, a method oftreating the bath consisting in mixing air and fuel dust prior toadmission to the furnace, and feeding such air and fuel dust mixture tothe furnace at a point from'the-surfacebf the bath not greater than thelength of the flame of combustion and in a direction to impinge on saidsurface.

In testimony whereof we affix [0111' signatures to this specification,in the presence of two witnesses;

GASTON BARBANSON.

MAX LEPERSONNE;

Witnesses:

GREGORY PHELAN, GFRBAULT.

